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Question Which of the following numbers are prime? 23, 51, 37, 26
23 = 1 × 23, 23 = 23 × 1
Since, 23 has only two factors i.e. 1 and 23.
Therefore, 23 is a prime number.
51 = 1 × 51, 51 = 3 × 17
Since, 51 has four factors i.e. 1, 3,17 and 51.
Therefore, 51 is not a prime number.
37 = 1 × 37, 37 = 37 × 1
Since, 37 has only two factors i.e. 1 and 37.
Therefore, 37 is a prime number.
26 = 1 × 26, 26 = 2 × 13
Since, 26 has four factor i.e. 1,2,13 and 26.
Therefore, 26 is not a prime number.